I need help making a boss entity

So I have never made a boss before, but I want to make one with projectile properties or some sort of summoning features. I'm not very experienced with using procedures but have played with procedures a little bit, and I don't have ANY knowledge in coding at all. I have watched video tutorials but the procedure blocks used in some of the videos don't show up for me. If anyone can share screenshots, that will help me better understand!

Thanks